Wolfe, if you're not comfortable with line voltage, don't mess with it. I do think everyone ought to learn the basics, though. Start by turning the power off. The whole main panel if that's what makes you comfortable. White to white, color to color other than green. Green and bare all bundled up together in each box.
I remember the first time I wired in a new circuit to an existing panel that was hot. I really couldn't kill the whole house because of so many things to reset. I was shaking like a leaf. Now I stick my hand in there like it's a bowl of noodles. Just got to know which noodle not to touch.
Old TV's and their capacitor is what scares the hell out of me.